Method for producing a silicon single crystal by a float-zone method

Abstract

A method of producing a silicon single crystal by the floating-zone method, comprising the steps of: providing a polysilicon rod having an average grain length of 10 to 1000 μm; heating a portion of the polysilicon rod to form a molten zone while applying a magnetic field of 300 to 1000 gauss to the molten zone; and passing the molten zone through the length of the polysilicon rod thereby the polysilicon rod is converted into a silicon single crystal ingot through a one-pass zoning of the floating zone method. An apparatus for reducing the method into practice is also described.

What is claimed is: 
     
       1. A method of producing a silicon single crystal by the floating-zone method, comprising the steps of: providing a polysilicon rod having an average grain length of 10 to 1000 μm;   heating a portion of the polysilicon rod to form a molten zone while applying a magnetic field of 300 to 1000 gauss to the molten zone;   passing the molten zone through the length of the polysilicon rod, thereby converting the polysilicon rod into a silicon single crystal ingot through a one-pass zoning of the floating zone method; and   post-heating the silicon single crystal being grown.   
     
     
       2. A method according to claim 1, wherein said post-heating the silicon single crystal being grown includes providing a reflector disposed around a portion of the silicon single crystal which is located immediately below the molten zone. 
     
     
       3. A method according to claim 1, wherein a solid-liquid interface between the polysilicon rod and the molten zone is held at a level equal or higher than an underside of an induction heating coil. 
     
     
       4. A method according to claim 1, wherein said magnetic field is a static magnetic field applied in a direction parallel to a direction of growth of the silicon single crystal. 
     
     
       5. A method according to claim 4, wherein said magnetic field is produced by exciting a solenoid coil with a direct current. 
     
     
       6. A method according to claim 5, wherein said solenoid coil is disposed around a portion of the silicon single crystal which is located immediately below the molten zone. 
     
     
       7. A method according to claim 5, wherein said solenoid coil is disposed around a portion of the polysilicon rod which is located immediately above the molten zone. 
     
     
       8. A method according to claim 1, wherein said magnetic field is a static magnetic field applied in a direction perpendicular to a direction of growth of the silicon single crystal. 
     
     
       9. A method according to claim 8, wherein said magnetic field is produced by exciting a solenoid coil with a direct current. 
     
     
       10. A method according to claim 9, wherein said solenoid coil is disposed around a portion of the silicon single crystal which is located immediately below the molten zone. 
     
     
       11. A method according to claim 9, wherein said solenoid coil is disposed around a portion of the polysilicon rod which is located immediately above the molten zone. 
     
     
       12. A method according to claim 1, wherein said magnetic field is a combination of a first static magnetic field applied in a direction parallel to a direction of growth of the silicon single crystal and a second static magnetic field applied in a direction perpendicular to the direction of growth of the silicon single crystal. 
     
     
       13. A method according to claim 12, wherein each of said first and second static magnetic field is produced by exciting a solenoid coil with a direct current.